Antiemetic

• An antiemetic is a medication or treatment used to prevent or alleviate nausea and vomiting.
• Nausea and vomiting, also known as emesis, can be caused by various factors, including motion sickness, chemotherapy, surgery, pregnancy, and certain medical conditions.
• Antiemetics work by targeting different pathways in the body that trigger the emetic response, providing relief and improving the patient's overall well-being.

Mechanism of Action

Antiemetics exert their effects through various mechanisms, including:

• Serotonin (5-HT3) receptor antagonism: Some antiemetics block the serotonin receptors in the brain and gastrointestinal tract, reducing the activation of the emetic pathway.
• Dopamine receptor antagonism: Other antiemetics target dopamine receptors in the brain, inhibiting dopamine-mediated signals that trigger nausea and vomiting.
• Histamine receptor antagonism: Certain antiemetics act as histamine receptor antagonists, inhibiting the histamine signals that contribute to the emetic response.
• Neurokinin-1 receptor antagonism: Some newer antiemetics block neurokinin-1 receptors, which play a role in the transmission of nausea signals to the brain.
• Cannabinoid receptor agonism: Cannabinoid-based antiemetics interact with cannabinoid receptors in the brain, modulating the neurotransmitter release involved in the emetic response.

• The specific choice of antiemetic depends on the underlying cause of nausea and vomiting, as well as individual patient factors such as age, medical history, and the potential for drug interactions.

Commonly Used Antiemetics

Here are some examples of commonly used antiemetic medications:

• Ondansetron: A selective serotonin receptor antagonist commonly used to prevent nausea and vomiting caused by chemotherapy, radiation therapy, and surgery.
• Metoclopramide: A dopamine receptor antagonist with both antiemetic and prokinetic properties. It is used to treat nausea and vomiting associated with various causes, including chemotherapy, gastroparesis, and migraines.
• Prochlorperazine: A dopamine receptor antagonist used for the management of nausea and vomiting associated with chemotherapy, surgery, and certain vestibular disorders.
• Dimenhydrinate: A histamine H1 receptor antagonist commonly used for the prevention and treatment of motion sickness.
• Aprepitant: A neurokinin-1 receptor antagonist used in combination with other antiemetics to prevent nausea and vomiting caused by highly emetogenic chemotherapy.
• Cannabis-based medications: Medications containing synthetic cannabinoids or natural cannabis derivatives may be used for refractory chemotherapy-induced nausea and vomiting, as well as in other specific cases.

Precautions

• Individuals with certain medical conditions or specific risk factors may require additional precautions when using antiemetics.
• Pregnant or breastfeeding women, individuals with liver or kidney disease, and those with a history of certain neurological disorders may need careful consideration of the risks and benefits of using antiemetic medications.

Adverse Effects

• Antiemetics, like any medication, can have potential adverse effects. These effects may vary depending on the specific medication used.

Common side effects may include:

• Drowsiness or sedation
• Dizziness or lightheadedness
• Dry mouth
• Constipation
• Blurred vision
• Restlessness or agitation
• Headache
• Muscle spasms or stiffness

• It's important to monitor patients for these side effects and adjust the medication regimen as needed. In some cases, the benefits of using antiemetics may outweigh the potential side effects, especially in individuals experiencing severe or persistent nausea and vomiting.

Contraindications

There may be certain contraindications to the use of specific antiemetics.

Contraindications may include:

• Hypersensitivity or allergy to the medication
• Severe liver or kidney disease
• Known drug interactions with other medications the patient is taking
• Certain medical conditions that may be exacerbated by the medication

See Also

• Nausea
• Vomiting
• Chemotherapy-Induced Nausea and Vomiting
• Motion Sickness
• Postoperative Nausea and Vomiting

Antiemetic Resources
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